Fully autonomous cars are coming, but concerns ranging from regulatory issues to the handoff between machines and humans need to be addressed before drivers can let go of the wheel – and trust the technology. In the meantime, we’ll likely be stuck in a middle ground of semi-autonomy between Level 2 and Level 3 over the next few years.

Systems such as Tesla Autopilot, Mercedes-Benz Steering Assist and Volvo Pilot Assist II can take over part if not most of the driving task but still require human supervision – and a certain level of trust on the part of the driver. In the case of the Mercedes Steering Assist and Volvo Pilot Assist II, occasional driver intervention is required, otherwise the system deactivates.

I had a chance to briefly test Volvo Pilot Assist II over the course of a day’s drive in a 2017 S90, but it was on unfamiliar roads at a press event in Spain. Recently I had the opportunity to spend a week with the system in another 2017 S90 on a highway I drive almost daily and in adverse weather.

As the name suggests, Volvo Pilot Assist II is not completely new. The first-generation of the system, which debuted on the 2016 Volvo XC90 SUV in 2015, combines adaptive cruise control that tracks a vehicle ahead with radar to accelerate and brake in tandem with traffic flow and lane-keeping assist that uses cameras to keep the car between the stripes. Pilot Assist II doesn't need to sense a vehicle ahead and can operate at speeds up to 80 mph, as opposed to 30 mph for the first-gen version.

Unlike the Mercedes-Benz Steering Assist, which employs sensors in the steering wheel to detect the tactile pressure of hands on the wheel (and defeats the system if it doesn't), Pilot Assist II looks for occasional steering inputs from the driver. On narrow Spanish roads I’d never driven before – and in heavy traffic – I was hesitant to trust Pilot Assist II and mostly kept my hands lightly on the wheel. In this situation, I didn’t fully trust the system and felt like I was playing tug of war against its driving input and my own instincts.

But on a wide interstate highway near home that I drive often, I found the system to be much more comfortable to use, even in heavy rain. I still noticed, as in Spain, a slight shifting of the car from one side of a lane to the other, and I felt like I wanted to intervene when the car veered strongly towards one side of a lane around curves.

Volvo's Pilot Assist II system cancels after a certain period of time if it doesn't detect steering input from the driver. Photo by Doug Newcomb.

All AV systems take some getting used to and require a certain leap of faith to trust them to semi-autonomously drive a fast-moving vehicle. But after a few days using Pilot Assist II in the 2017 Volvo S90, I found a sweet spot and could go for long stretches with only occasional steering input.

But the system still requires near constant attention and isn’t even close to full autonomy. My time with Volvo’s Pilot Assist II made me think that the technology still has a way to go before drivers can completely kick back and let the car drive – and totally trust the technology.